1. Field of the Invention
The present invention relates to an implantable device for drug delivery and dialysis, particularly for peritoneal dialysis, and a method of using the system.
2. Description of the Related Art
Kidney failure is typically treated by dialysis until a kidney transplant or other treatment can replace the kidney function. Dialysis can be performed by hemodialysis or peritoneal dialysis (PD).
Hemodialysis treatment removes the blood from the body, often about 0.25 L (8.5 fl. oz.) at a time, and often from a blood vessel in the arm. The extra-corporeal blood is then passed through a semi-permeable membrane that removes the waste—including excess water—otherwise filtered by healthy kidneys, from the blood without the loss of desirable molecules. Hemodialysis patients typically receive three treatment sessions per week, with each session lasting 3 to 5 hours. Because proper maintenance of hemodialysis equipment (e.g., membranes, pumps) is critical, hemodialysis sessions are often performed at a treatment center.
PD treatment introduces a dialysis solution to the peritoneal cavity. The blood is naturally filtered through the organ membranes in the peritoneum. Blood waste naturally passes through the organ membranes in the peritoneal cavity. The waste is drawn into the peritoneal cavity by the osmotic pressure gradient created by the properly-formulated dialysis solution. After a few hours, the dialysis solution, loaded with waste, can be removed. A patient can perform the “exchanges” of dialysis solution at home, but must drain an extra-corporeal bag of dialysis solution into the peritoneal cavity, and then drain their own peritoneal cavity into an extra-corporeal bag—all through a trans-peritoneum catheter. Patients also usually undergo four to six exchanges a day.
PD is widely considered to be a more effective treatment for removing waste from the blood, but patients often prefer the relative infrequency and convenience of hemodialysis. Most patients also prefer not to receive the large quantity and depth of the punctures associated with PD.
U.S. Pat. No. 5,037,385 to O'Byrne discloses an implantable peritoneal dialysis system. The system includes an implanted trans-peritoneum catheter. The trans-peritoneal catheter terminates outside the peritoneal cavity at a subcutaneous self-sealing terminal structure and terminates inside the peritoneal cavity at an open end. Dialysis solution can be introduced directly into the subcutaneous self-sealing terminal structure. The solution then flows into the peritoneal cavity. The system also includes an implanted catheter that drains the peritoneal cavity into the bladder via a pump.
The system disclosed by O'Byrne may reduce the number of times the patient must drain their peritoneal cavity and may reduce the depth of the punctures needed to introduce dialysis solution to the peritoneal cavity. The system disclosed by O'Byrne, however, fails to increases the number of painful punctures needed to introduce the dialysis solution, fails to incorporate safeguards against pathologically high pressures in the urinary bladder or pathologically low levels of peritoneal fluid, fails to incorporate control mechanisms required for effective dialysis without dehydration, and fails to prevent loss of peritoneal proteins with extended use.
A need therefore exists for methods and devices for performing more convenient and painless PD. There exists a need to reduce the frequency of punctures patients receive during PD treatment. There also exists a need to reduce the depth of punctures during PD therapy. Furthermore, there exists a need to fulfill the above needs without negatively affecting the quality of blood waste removal.